Frontal dynamics and water mass variability on the Campbell Plateau

Abstract

The Campbell Plateau is a dominating bathymetric feature of New Zealand’s subantarctic region, strongly influencing the dynamics of both the Subtropical Front (STF) to the north and the Subantarctic Front (SAF) to the south. We present a consistent survey across New Zealand’s subantarctic of the relationships between front positions, bathymetry and water masses. The northwest side of the Campbell Plateau is comparatively warm due to a southward extension of the STF over the plateau. The SAF is steered south and east by the combined effect of the plateau and Macquarie Ridge, with waters originating in the SAF also found north of the plateau. Formation of Subantarctic Mode Water (SAMW) is confirmed, with a deep reservoir of SAMW persisting nearly a year after formation. Antarctic Intermediate Water (AAIW) is observed around the edges of the plateau, but not present on the plateau, confirming that the waters on the plateau are isolated from deeper Southern Ocean.